Simple furnace maintenance you can do yourself

Posted10/2/2021 6:00 AM

Q: My furnace seems to be working properly, but I want to keep it running at its highest efficiency. Are there any simple furnace maintenance tasks I can regularly do myself?

A: A furnace, especially today's models with all the electronics, is a complicated piece of equipment, but there are some simple things you can do yourself to maintain its efficiency. Your summer air-conditioning costs will also be lower because it uses the same air handler (blower) as the furnace.


If you decide to do some of the maintenance yourself, don't skip the regular professional checkups. Many serious problems with a furnace do not present any noticeable symptoms, so only a professional can detect them. Some not only increase your utility bills, but can be dangerous.

Check how much energy your house uses from year to year. Compare the actual usage of gas, oil, electricity, etc., not just the bills. Also, factor in the variation in severity of the weather from year to year. Energy usage for lighting, water, heating and appliances does not vary much year to year.

Always check the safety items first for your annual maintenance check. Drip some soapy water on gas and propane line fittings. Look for bubbles that indicate a leak. If you find a leak of any type, leave immediately and call your gas company. You will generally see and smell a fuel oil leak.

Visually inspect the electric wire insulation leading to the furnace, but do not touch it. If you see any bad spots, switch off the circuit breaker first before checking them more carefully. Make sure to get all the circuit breakers because an electric furnace uses 240-volt current.

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With the electric power switched off, unscrew and remove the side cover to gain access to the blower. A clean blower moves room air more efficiently, and it helps keep the heat exchanger surfaces clean. They also transfer heat (and cooling during summer) when they are clean.

Use a vacuum cleaner brush attachment to clean any dust deposits off the blower. Wipe any surfaces with a damp rag to pick up more dirt. Some older systems have bearing oil cups on the motor. Put a drop of oil in each cup. This is a good time to change or clean the central furnace filter.

It is important to tighten the screws when you replace the side cover. Also check all the other screws for tightness. If they are loose, air can leak in through gaps instead of flowing through the heat exchanger. This can reduce efficiency. With a heat pump, also check the screws on the outdoor unit.

Ductwork is often very leaky and the heated air never gets to the rooms. Turn up the thermostat so the furnace starts. Hold your hand near each duct joint to find leaky spots. Clean the dust off the duct and wrap those spots with black Gorilla tape.


Check the accuracy of the thermostat by temporarily taping a bulb-type thermometer next to it on the wall. You may be keeping your house several degrees warmer than you thought you were and this increases your utility bills.

Q: I was up in my attic and noticed a large gap between my brick chimney and the attic floor. I could feel a light breeze flowing upward through it. What is the best method to block this leak?

A: Cut aluminum flashing material slightly larger than the distance from the joists to the chimney. Lay a bead of caulk on top of the joists and nail the flashing to them. Bend the edge down over the side of the joist.

Using a piece of lumber as a straight edge, hammer it against the other end of the flashing and the chimney to form an upward bend tight against the chimney. Run a heavy bead of caulk to seal it against the chimney.

• Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit

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